This invention relates to coated medical devices. More specifically, it relates to medical devices which have a contact surface exposed repeatedly to bodily tissue, and where the contact surface has a coating to enhance lubricity while providing the durability necessary to provide that lubricity during the repeated exposure to the tissue.
Coated medical devices, which repeatedly come into contact with bodily tissue, for example surgical needles, are required to be lubricious, yet durable to withstand the multiple contacts with tissue. However, lubricity is often sacrificed at the expense of making a more durable coating that adheres well to medical devices. There are many coating materials that are extremely lubricious, but either do not adhere well to the desired substrates or easily wear off the substrate during use. Likewise, many extremely durable coatings exist, but these coatings are not considered lubricious. Consequently, conventional coated medical devices are unable to maintain lubricity as the devices are used successively because the coatings wear away, such as with a surgical needle that is passed through tissue a number of times.
A highly favored lubricious material that is used as a coating for many medical devices such as surgical needles and catheters is silicone. However, as discussed above in the context of conventional lubricious coating materials, the silicone coating generally wears off the medical device with repeated exposure to tissue. For example, when a needle coated with silicone is successively passed through tissue during wound closure, the silicone coating wears off appreciably with each pass, resulting in an increase in penetration force each time the needle is passed through the tissue.
Examples abound in connection with enhancing the properties of silicone coated medical devices by adding ingredients to modify the overall properties of the silicone coating. For example, hydrophilic surfactants, including hydrophilic polymeric surfactants, have been mixed with silicone coating solutions and applied to medical devices such as catheters and needles. Unfortunately, the incorporation of these hydrophilic polymers does not add significantly to the durability of the silicone coating on these medical devices.
In view of the inability to develop a coating for a medical device which provides lubricity without sacrificing the durability of the coating over successive uses, what is needed is a coated medical device, in particular a medical device coated with a silicone, which will provide these properties simultaneously.